Study Objective: The measurement of height is a critical outcome indicator in many pediatric protocols. Since there is no gold standard for height measurement, an average of 10 individual height measurements has been used in NICHD protocols. No known published research studies support this number of height measurements. A review of the literature suggested the theoretical need for 3 individual measurements at most. The purpose of this study is to determine whether there are significant within-day and/or day-to-day differences between the average of 10 height measurements and the average of 3 height measurements in pediatric patients. Methods: Seventy-one children will undergo 20 height measurements (10 on each of 2 separate days) using standard techniques. Data will be analyzed via two-tailed T-test. Summary and Findings: Data have been collected on 30 subjects. Data collection continues.